LG has applied for a pair of patents on dual-screen smartphones, with one application covering a traditional slider with two displays (pictured top), while the other describes a unique body style utilizing a gear-driven opening and closing mechanism. These devices both employ one display for viewing content, while the other screen can be customized for a number of uses, such as virtual keyboard, media control pad, or even an extension of the first display (likely useful for viewing large web pages or showing more of a map).

The slider is envisioned to behave much like a Nintendo DS, with the bottom display used for navigation and control of the primary content (pictured above), or as a secondary monitor to view larger versions of website images, for instance. Similarly, a video playing in the primary display could be pushed down to the bottom screen, allowing the user to continue web browsing up top.

Even more interesting is the other dual-display unit (pictured above and below), which utilizes a set of gears to push the secondary display out of the phone housing when the primary screen is tilted at an angle. This results in a configuration somewhat similar to the HTC TyTN II, HTC Touch Pro 2, or Nokia N97, but looks to be more stable due to the body of the phone extending well behind the screen. We have to admit to being quite intrigued by such a form factor, although we’re a bit skeptical that LG could pull this off without bulking up our pockets too much.

This would the second time in as many weeks that we’ve come across devices which eschew hardware keyboard for touch panel input, with Acer having just debuted its Iconia laptop featuring a pair of hinged 14-inch displays. Toshiba, meanwhile, has its own dual-screen portable in the Libretto W105, whose seven-inch screens are both touch-sensitive capacitive displays. Then there’s Nintendo, which has raised the multi-display bar by incorporating a glasses-free 3D display in its latest mobile console, the Nintendo 3DS.

LG itself has already experimented with dual-screen production devices in the form of the enV Touch and unreleased enV Pro, although those handsets sport a hardware keyboard alongside internal and external screens.